From DE 43 05 700 C1, a breech of a repeating rifle according to the class is known. In that document, a locking chamber and a locking sleeve arranged concentric about this locking chamber are arranged within a locking guide that is displaceable on a system casing. The locking sleeve constructed as an expansion sleeve is divided on its front end by longitudinal slots into several flexible spring tongues. The spring tongues have, on their front ends, locking elements for engaging in an annular groove on the inside of the barrel. By means of an expansion cone provided on the locking chamber, the locking elements constructed integrally with the spring tongues of the locking sleeve can move between a radially inner unlocked position and a radially outer locked position. For this known breech, the expansion of the locking sleeve constructed as an expansion sleeve is achieved by its axial displacement against the expansion cone formed on the locking chamber.